We are studying the genetic organization and expression of SV40 and adenovirus 2 by an analysis of the SV40 and Ad2 genomes contained within Ad2-SV40 hybrid virus DNA molecules. The hybrid viruses are also employed as models for understanding the behavior of integrated genomes. We are also analyzing the behavior of SV40 hybrid virus DNA molecules. The hybrid viruses are also employed as models for understanding the behavior of integrated genomes. We are also analyzing the behavior of SV40 and Ad2-transformed or lytically infected cells as a function of the molecular conformation of viral nucleic acids within these cells, and as a function of events which may control (or be controlled by) viral replication, transcription, and translation. Secondly, we are analyzing the state and expression of the endogenous AKR murine leukemia virus genome in mice with varying expression of leukemia and virus production. A further objective is to explore the evolution, transmission, and relation to leukemogenesis of various murine RNA viruses. Finally, this laboratory is concerned with production and purification of Epstein-Barr virus DNA and the use of this reagent to explore molecular mechanisms of infection and oncogenicity associated with this human herpes virus. Studies of cell lines from human lymphomas include surface markers, karyotypes, presence of and infectibility by EBV, growth characteristics, and morphology. New EBV strains from African Burkitt's (true tumor strains?) are studied. BIBLIOGRAPHIC REFERENCES: Breeden, J.M., Wewerka-Lutz, Y., Schnipper, L.E., Hauser, J., Patch, C.T., Lewis, A.M., Jr. and Levine, A.S.: The content and expression of integrated viral DNA in hamster cells transformed by the nondefective adenovirus 2-simian virus 40 hybrid viruses. J. Virol. 20: 555-563, 1976. Everitt, E., Meador, S.A. and Levine, A.S.: Synthesis and processing of the precursor to the major core protein of adenovirus type 2. J. Virol. 21: 199-214, 1977.